Mylar film, either in microfiche form or in a roll, often is used for photographically recording highly sensitive information. Mylar film is a highly oriented polyester. When the decision is made to destroy this recorded information it is necessary that the destruction be so complete as to eliminate the possibility that an unauthorized person might reconstruct a useful amount of the putatively destroyed information.
My copending U.S. patent application Ser. No. 07/299,796, filed Jan. 23, 1989, discloses an apparatus for scraping photographic images from a Mylar or other film member which comprises:
feed rollers and pressure rollers for advancing the film member along a predetermined straight-line path without slippage between the feed rollers and the film member;
a first abrading roller and pressure rollers for scraping off segments of the photographic images at certain locations across the width of the film member.
a second abrading roller nd pressure rollers for scraping off the remaining segments of the photographic images at their locations across the width of the film member;
and a motor drive arrangement for the feed rollers and the abrading rollers which rotates the abrading rollers at a much higher surface speed than the feed rollers, so that the surface speed of each abrading roller is much higher than the speed of the film member moving tangentially past it.
The pressure rollers that coact with the feed rollers are heavily spring-biased toward the feed rollers to prevent slippage of the film member, and the pressure rollers that coact with the abrading rollers are of relatively soft yieldable material and are lightly spring biased toward the abrading rollers. The scraping action of each abrading roller takes place on the film member at a different location along its path than the clamping action of each feed roller and the respective pressure roller so that any given longitudinal segment of the film member sequentially experiences clamping, abrading and clamping actions.